Electronic pattern circular knitting machines are currently in extensive use in the production of knitted fabrics of various designs from relatively simple to very complex. Typically, circular knitting machines include a rotatable needle cylinder having a multiplicity of grooves in the outer periphery parallel to the axis of rotation of the cylinder, each of which contains a knitting needle for reciprocation between a plurality of operative and inoperative positions. The rotatable needle cylinder cooperates with a rotatable, horizontal dial having a multiplicity of radial grooves in the upper surface thereof, each of which contains either a dial needle or a sinker depending on the type of knitting machine. The cylinder and dial are driven in rotation by a drive mechanism and the cylinder needles and dial needles or sinkers are moved past respective stationary cams which reciprocate the cylinder needles and dial needles or sinkers.
Since the cylinder needles and dial needles or sinkers cooperate in the knitting operation, the timing of the operation thereof is very important. Examples of such timing are synchronous and delayed. As knit patterns are changed, it is frequently necessary to change the knitting timing by changing the position of the needle cams. Of course, any change in the knitting timing must be correlated to the electronic pattern control and needle selection mechanism, which may be difficult and historically has been time consuming and expensive.
In Japanese Patent Provisional Publication No. 298857/1998 (Japanese Patent Application No. 113469 of 1997), it is proposed to employ an optical encoder associated with the needle cylinder for monitoring the position of each knitting needle and therefore determining changes in the timing of the needles by the cams associated with such knitting needles. While an improvement over conventional technology, this proposed arrangement has the disadvantage of only accommodating timing changes with respect to the knitting needles on the cylinder and therefore cannot accommodate timing changes with respect to dial needles or sinkers.